Method for sewing various kinds of articles, in particular made of leather, and machine for carrying out this method

ABSTRACT

A method for sewing leather articles includes positioning one edge of a first article (8) and one edge of a second article (9) to be sewn together against respective flat side surfaces (7a,7b) of a longitudinal guiding plate (7) formed at the top of a ring-like block (11). The ring-like block (11) rotates on a pin (12) that is supported, with horizontal axis and perpendicular to said guiding plate (7), by a free end of an arm (13) that swings with respect to a stationary support frame (2). The edges of the articles (8,9) are sewn together by means of an arc-shaped needle (6), which is reciprocated on a plane transversal to the guiding plate (7), between a retracted position, in which the needle is located beside one of said flat side surfaces (7b) and a piercing position, in which the needle pierces said articles (8,9); the needle (6) is moved forward and backward according to a predetermined step. Sewing of said articles (8,9) is followed by swinging said arm (13) together so that spatial attitude of the guiding plate (7) is kept unchanged as the sewing progresses.

TECHNICAL FIELD

The present invention concerns sewing articles made of leather and thelike, in particular for footwear production.

BACKGROUND ART

Known automatic machines for sewing leather articles usually feature ahead, cantilevered on the front of the base structure and equipped withmeans for supporting the needle and related operating means.

The needle is moved toward an arm, which is situated below, that acts asa horizontal support, on which the leather articles to be sewn rest. Theneedle moves also in a direction parallel to the support arm.

The above mentioned machines are equipped also with transport means thatmove the two edges of leather articles to be sewn positioned one overthe other, after each stitch.

A machine of this type is disclosed in the U.S. Pat. No. 4,848,252 byApplicant. This machine features a guide with two longitudinal flatsurfaces, upwardly convergent, that form respective work tops, on whichthe leather articles to be sewn are moved.

Over the guide, there is provided a longitudinal shaft, with an armkeyed thereto and provided at its free extremity with an arc-likeneedle. The shaft oscillates so as to alternatively move the needlebetween a raised position and a lowered position, in order to pierce theedges of the leather articles. The needle operates in combination with arotary hook with a thread.

The above mentioned machine sews edges of two leather articles, e.g.shoe uppers and toe caps.

However, this machine cannot be used for sewing together the bottom andthe upper, in case the shoe is of open type and a strip is to be joinedto the bottom.

FIG. 12 shows, as an example, a shoe with an upper sewn along its edgeto a bottom.

It is to be noted that in this case the sewing is visible both along theedge of the upper and along the edge of the bottom, thus forming a kindof decorative motif.

At present, the sewing of the bottom to the upper is often hand-made,that requires a specialized staff thus increasing manpower cost andsubsequently, the final cost of the product, and moreover, theproductivity is reduced.

Another problem deriving from the hand-made sewing lies in the necessityof a camber that is made in front part of the shoe by previously shapingthe front part of the upper like a dome.

Other known automatic machines, so-called "Rapid", can sew the bottom tothe shoe upper.

However, the use of these machines requires former joining of the bottomand the upper by means of glue; moreover, the shoe must be mounted on asuitable last during sewing.

Obviously, this results in considerable working complexity andconsequently, affects the cost of the product and the productivity.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a method forsimplified sewing of leather articles, in particular the bottom and theupper of a shoe, without preliminary operations.

Another object of the present invention is to provide a machine thatcarries out the above mentioned method of sewing and that has a simplestructure and is versatile in relation to different kinds of footwear.

The above mentioned objects are obtained in accordance with theinvention by means of a method for sewing various kinds of articles, inparticular made of leather, that includes:

positioning one edge of a first article and one edge of a second articleto be sewn together against respective flat side surfaces of alongitudinal guiding plate formed at the top of a ring-like block, whichrotates on a pin that is supported, with a horizontal axis andperpendicular to said guiding plate, by a free end of an arm that swingswith respect to a stationary support frame; sewing said edges of saidarticles together by means of an arc-shaped needle that is reciprocatedon a plane transversal to said guiding plate, between a retractedposition, in which the needle is located beside one of said flat sidesurfaces and a piercing position, in which the needle pierces saidarticles, said needle being moved forward and backward according to apredetermined step; swinging said arm while sewing the two articlestogether so that the spatial attitude of said guiding plate is keptunchanged as the sewing progresses.

The method is carried out by a machine that includes:

one longitudinal guiding plate, which defines two opposite flat sidesurfaces against which said articles are positioned while being movedforward, said guiding plate featuring a shoulder for abutment thereon ofsaid first articles;

an arc-like needle, which reciprocates on a plane that is transversal tosaid guiding plate between a retracted position, in which the needle islocated beside one of said flat side surfaces and a piercing position,in which the needle pierces said articles, said needle being movedforward and backward according to a predetermined step;

a rotary hook assembly and a thread spool located beside the other oneof said flat side surfaces for cooperation with said needle to form thestitches; means movable in a direction transversal to said guiding plateto abut on and clamp said articles during needle piercing and retractionrespectively;

a ring-like block, whose top carries said guiding plate, that isrotatably supported by a horizontal pin transversal to said guidingplate and fastened to a free end of an oscillating arm, which swingswith respect to a stationary frame;

a device for keeping the spatial attitude of said guiding plateunchanged when said oscillating arm swings.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention will be better understood from thefollowing description, with particular reference to the attacheddrawings, in which:

FIG. 1 is a front view of the present machine for sewing leatherarticles;

FIG. 2 is a partial side view of the same machine;

FIGS. 3 and 4 are perspective views of the stitching zone of the machinebeing the subject of the present invention, seen at different angles;

FIG. 5 is a perspective view of the bottom and the upper of a shoe to besewn by the subject machine;

FIG. 6 is a perspective view of the whole above mentioned stitchingzone, during introduction of the articles to be sewn;

FIG. 7 is a detailed view of the stitching zone of the machine, duringworking step, as viewed substantially at the same angle as FIG. 3;

FIGS. 8a and 8b are respectively, perspective views of the stitchingzone, seen at the same angle as in FIG. 4, in subsequent working steps;

FIG. 9 is a vertical section view of a detail of the above mentionedstitching zone;

FIGS. 10 and 11 are further perspective views, seen at different angles,of the machine stitching zone in subsequent working steps;

FIG. 12 is a perspective view of a shoe sewn according to the presentmethod;

FIGS. 13 and 14 are views corresponding to FIGS. 1 and 9 for a variationof the machine.

BEST MODE OF CARRYING OUT THE INVENTION

With reference to the above mentioned figures, numeral 1 indicates thehead of the sewing machine, that carries means for operating sewingmeans.

The head 1 is an integral part of a stationary support frame 2 of themachine; in particular, the head 1 is cantilevered on the front of abody 3 of the frame 2, whose axis is suitably inclined with respect tothe vertical.

The head 1 supports, in a known manner, a longitudinally oriented shaft4 provided with a transversal arm 5. A curved needle 6 is tangentiallymounted on an end of the transversal arm 5 and extends along a virtualcircumference that is concentric with the shaft 4.

The needle 6 oscillates between a retracted position, beside the workplans of the guiding plate 7, as specified in the following, and apiercing position, in which the needle 6 passes through the articles 8and 9 to be sewn.

These articles 8 and 9 in particular include the bottom and upper of ashoe. The needle 6 oscillates in a suitable phase relation with theadvancement movement of the leather article to be sewn.

The shaft 4 of the needle 6 is reciprocated axially so at to moveforward and backward according to a predetermined step, and impart aforwarding motion to the articles 8,9 to be sewn.

A rotary hook 10, with a thread spool, works in cooperation with theneedle 6. The rotary hook 10 is situated beside the work plans of theguiding plate 7 on the side opposite to the side where the needle restswhen in retracted position.

As seen in detail in FIG. 9, the guiding plate 7 is laterally delimitedby flat surfaces 7a,7b, which are substantially vertical.

The flat surfaces 7a,7b form respective working plans for positioningand guiding the articles 8 and 9 to be sewn.

Below the working plan 7a, the guiding plate 7 forms a shoulder 7c forabutment thereon of the internal edge of the article 8.

The guiding plate 7 is formed at the top of a ring-like block 11, whichrotates on a pin 12 with horizontal axis. The pin is supported by a freeend of an arm 13 that swings with respect to a stationary support frame2.

A rim presser 14, is situated over the guiding plate 7, for pressing theedge of the articles to be sewn by means of a shaped head 15.

The position of the rim presser 14 is vertically adjustable because itis fixed by means of a locking member 18 that passes through a verticalslot 17 made. Releasing the locking member 18 and displacing the rimpresser 14 makes it possible to change the height of the articles 8,9over the guiding plate 7 and consequently, the position of the sewingline with respect to the edges of the articles.

According to a constructive variation, not shown, the head 15 of the rimpresser 14 includes two elements, drawn close one to the other, that actrespectively in the regions of the edges of the articles 8,9 and thatcan be adjusted independently so as to regulate the mutual position ofthe articles 8,9.

In the shown example, the rim presser 14 remains stationary in thepre-fixed position, but it is possible for the rim presser 14 to bevertically displaced for particular working needs, e.g. introduction andwithdrawing the articles 8, 9 to be sewn.

A presser foot 19 is formed at the end of an arm 20 and is situatedbeside the working plan 7a of the guiding plate 7.

The arm 20 is moved, by known means, in direction transversal to thestitching line being formed and longitudinal to the same line insynchrony with the needle 6 movement direction; the foot 19 has athrough hole 21, through which the needle 6 passes freely.

During piercing motion of the needle 6, the foot 19 rests against thebottom 8 to hold it.

A leather pressing element 22, situated beside the working plan 7b,moves in direction transversel to the stitching line being formed andkeeps the articles 8,9 after each stitch has been performed, when theneedle 6 is being withdrawn.

A crumpling group 23, also situated beside the working plan 7b,reciprocates backward and forward in direction longitudinal to theguiding plate 7 and in direction transversal thereto.

The group 23 supports a head 24, equipped with a transversal peg 25 thatengages the article 9, i.e. the shoe upper, so as to crumple the edge ofthe same upper being sewn, as it will be described in the following.

The ring-like block 11 is a part of a device 26 that keeps unchanged thespatial attitude of the guiding plate 7.

A device of this type is described in a detailed way in the ItalianUtility Model No. 0216423 of the same Applicant.

In particular, the lower part of the circumferential surface of thering-like block 11 features a toothing 27 that engages with a horizontalworm screw 28, which is supported below the said ring-like block 11 by acouple of plates 29, integral with the arm 13 (FIG. 3).

The worm screw 28 is joined to motion transmission means 30 that operatea gear, not shown in the drawing, engaging with a sector of a ring gear31 that is integral with the stationary support frame 2, on a verticalplan, parallel to the above mentioned working plans of the guiding plate7.

This toothed section ring gear is coaxial with a pivot 32, on which anoscillating support 33 of the arm 13 rotates operated by a motor 34,e.g. commanded by means of pedals or the like.

The operation of the described machine will now be illustrated beginningfrom introduction of the articles to be sewn, in this particular casethe bottom 8 and the upper 9 of a shoe; the upper 9 is of open type,i.e. is formed by a strip to be joined with the bottom 8 along an edge(FIG. 5).

The upper 9 is placed on the arm 13 supporting the ring-like block 11(FIG. 6). In this way it is possible to position the edges of the bottom8 and of the upper 9 each one against a respective working plan 7a,7b ofthe guiding plate 7.

In order to facilitate the articles introduction, the arm 13 carryingthe ring-like block 11 can be lowered, e.g. by rotating the support 33by suitable actuator means. Otherwise, already mentioned, it is possibleto raise the rim presser 14.

In the working position, the rim presser 14 abuts on the upper part ofthe edges of the bottom 8 and the upper 9 (FIG. 7).

In this arrangement, rotation of the needle 6 to the piercing positionperforms, in conjunction with the action of the rotary hook 10, a stitchon the above mentioned edges of the bottom 8 and the upper 9.

The needle 6 follows a circular path (FIG. 8a). After having passedthrough the edges of the bottom 8 and the upper 9, the needle 6 reachesthe working zone of the rotary hook 10 (FIG. 8b). In this region theloop formed in the thread of the needle 6 is hooked, due to theoscillation of the rotary hook 10, in a known manner.

It is to be noted that, during the needle 6 piercing movement, thepresser foot 19 engages the upper part of the peripheral groove 35 ofthe bottom 8, so as to abut on the same bottom 8 and, indirectly, on theupper 9 (FIG. 9), the needle 6 passes through the hole 21 of the foot19.

After the needle 6 has passed through the edges of the bottom 8 and theupper 9, the articles 8, 9 are moved forward on the guiding plate 7.

In fact, this movement is determined by the longitudinal translation ofthe needle 6, which makes the articles 8,9 slide on the guiding plate 7.

When the longitudinal translation has been completed, the leatherpressing element 22 is imparted with an oscillation on a planetransversal to the guiding plate 7 so as to clamp the edge of the upper9 to the guiding plate, in a position adjacent to the just made stitch.In this manner also the bottom 8 is locked (see again FIG. 8b).

This allows to keep the stitched zone of the articles 8 and 9, when theneedle 6 rises, so that the thread hooked by the rotary hook 10 formsthe loop.

At this point, the needle 6 together with the rotary hook 10 arelongitudinally translated in a direction opposite to the forwardmovement direction of the articles 8, 9, so that the initial conditionsare restored, in order to perform next stitch.

During the return stroke of the needle 6, the bottom 8 and the upper 9are kept firmly by the leather pressing element 22.

Stitching advancement, determined by the forwarding action of the needle6 on the articles 8 and 9, is followed by the operator who suitablyrotates the shoe so as to guide the edges of the articles 8,9 along thestitching path defined by the guiding plate 7 (FIG. 10) and by the rimpresser 14.

The same operator rotates the oscillating support 33 of the arm 13 onthe pivot 32 in one direction or another to prevent the arm 13 frominterfering with shoe rotation while sewing (FIG. 11) is performed.

It is to be pointed out that the oscillation of the support 33 and thearm 13 does not affect the ring-like block 11 position and consequentlythe guiding plate 7 position remains unchanged, since the effect of therotation of the same support 33 on the pivot 32 is completely eliminatedby counter-rotation imparted to the same ring-like block 11 by thedevice 26.

In fact, any rotation of the support 33 is transmitted to the worm screw28 by the motion transmission means 30 that engage the ring gear 31;analogously, the worm screw 28 rotates axially in one direction oranother, according to the rotation of the support 3, causing the abovementioned counter-rotation of the ring-like block 11, engaged with thesame worm screw 8 by means of the toothing 27.

Therefore, in the arrangement provided for sewing, the spatial attitudeof the guiding plate 7 remains unchanged.

The operator can also activate the group 23 that allows to performcrumpling of a sewing edge, in particular that of the upper 9.

This crumpling is provided in the regions of the shoe tip and heel and,in particular includes increase of the movement of the upper 9 leatherwith respect to the bottom 8, so as to compensate for bigger peripherallength of the same upper.

A spontaneous bulge of the upper, in correspondence with the tip, isobtained by the above mentioned procedure avoiding the usual cambermaking operation, already mentioned before.

Crumpling beginning and end points, whose value may be changed by means,which are not shown, included in known way in the head 1 of the sewingmachine, are marked on the upper by the usual working procedure.

When the crumpling group 23 is activated, it moves first in directiontransverse to the guiding plate, so as to bring the head 24, fitted witha transversal peg engaged with the upper 9 (FIG. 8a) and then inlongitudinal direction so as to determine crumpling of the upper edge.

The crumpled edge of the upper 9 remains clamped between the head 24 andthe guiding plate 7 until the needle 6 is operated to perform nextstitch.

FIGS. 13 and 14 show respective views of the machine modified accordingto a variation. In this modified version, the head 1 is inclined in adirection opposite with respect to that of FIG. 1.

To obtain this configuration, the support body 103 is in fact rotatedover a 180 degree angle.

The result is that the needle moves along a virtual circumference indownward direction, instead of an upward direction as for the embodimentof FIG. 1.

In particular, taking into consideration the above mentionedcircumference, while the needle of FIG. 1 runs along an arc extendingfrom about 270 degree on, the needle of FIG. 13 runs along an arcextending from about 225 degree on.

The guiding plate 107 must be shaped so as to allow the needle to workalong a path different from that of FIG. 1. In particular, the inclinedworking plan 107b that receives the upper 9 of the shoe is situated on aside of the guiding plate 107 where the needle enters the articles to besewn.

On the contrary, a flat working plan 107a, receiving a pre-sole 108, issituated on the side where the needle exits, while going downwards. Alsothe presser foot 119 must match the different shape of the guiding plate107 and allow the needle to move along a different path.

This variation is suitable for carrying out the so called St. Crispinoor Ideal seams for particular kinds of shoes.

The above described machine, acting according to the subject method,allows to automatically perform stitching of leather articles like thebottom and the upper of footwear.

In particular, this operation does not need previous gluing of the edgesto be sewn and mounting of the shoe on a suitable last during the sewingstep.

The machine allows to produce footwear of the type illustrated in FIG.12, in which the sewing is seen both along the upper 9 edge and alongthe bottom 8 edge.

It is possible to flesh the upper 9 edge at a suitable angle, incorrespondence with the joining surface facing with the bottom 8, so asto delimit a suitable angle between the stitches of the upper 9 sewingline and the stitches of the bottom 8 sewing line, suitably alignedalong the groove 35.

The structure of the machine allows to vary the above mentioned angle,of the appropriate value chosen between a maximum and minimum, inrelation to the aesthetic characteristics to be obtained.

Moreover, the machine allows to crumple a sewing edge, in particular theedge of the upper.

It is to be pointed out that the above mentioned operation is carriedout in a simple way during a normal sewing cycle of the machine, withoutchanging working periods and functionality of this cycle.

Therefore, it is not necessary to form the camber as previouslydescribed, i.e. forming the shoe front part in the shape of a dome.

Obviously, it is possible to produce also footwear without crumplingalong the upper edge, according to the requested model.

I claim:
 1. A method for sewing various kinds of articles made ofleather, which comprises:positioning one edge of a first article and oneedge of a second article to be sewn together against respective flatside surfaces of a longitudinal guiding plate formed at the top of aring-like block, which is rotatable on a pin that is supported, with ahorizontal axis perpendicular to said guiding plate, by a free end of anarm that is swingable with respect to a stationary support frame; sewingsaid edges of said articles together by an arc-shaped needle that isreciprocable on a plane transverse to said guiding plate, between aretracted position, in which the needle is located beside one of saidflat side surfaces, and a piercing position, in which the needle piercessaid articles, said needle being movable forward and backward; swingingsaid arm while sewing the two articles together so that a spatialattitude of said guiding plate is kept unchanged as the sewingprogresses.
 2. A machine for sewing various kinds of articles made ofleather, which comprises;a longitudinal guiding plate, which defines twoopposite flat side surfaces, said articles being positioned each oneagainst a respective surface while said articles are movable forward,said guiding plate having a shoulder for abutment thereon of a firstarticle of said articles; an arc-like needle, which is reciprocable on aplane that is transverse to said guiding plate, between a retractedposition, in which the needle is located beside one of said flat sidesurfaces and a piercing position, in which the needle pierces saidarticles, said needle being moved forward and backward; a rotary hookassembly located beside the other one of said flat side surfaces forcooperation with said needle to form the stitches; a mechanism movablein a direction transversal to said guiding plate to abut on and clampsaid articles during needle piercing and retraction respectively; aring-like block having a top which carries said guiding plate said blockbeing rotatable supported by a horizontal pin transverse to said guidingplate and fastened to a free end of an oscillating arm which swings withrespect to a stationary frame; a device for maintaining the spatialattitude of said guiding plate unchanged when said oscillating armswings.
 3. A machine as in claim 2, wherein said flat surfaces of saidguiding plate (7) are substantially vertical and define respectiveworking planes on which edges of said articles (8,9) to be sewn togetherrest.
 4. A machine as in claim 2, which comprises:a toothing positionedalong the outer surface of said ring-like block; a worm screw supportedby said oscillating arm and in mesh engagement with said toothing, saidworm screw being connected to said attitude maintaining device; atransmission provided for coupling said worm screw to a ring gear sectorfastened to said stationary frame and which lies on a vertical planeparallel to said guiding plate; a pivot that is concentric with saidring gear sector; a swing support mounted on said pivot sector anddriven by a motor, said support supporting said oscillating arm.
 5. Amachine as in claim 2, which comprises a crumpling group situated besidea flat side surface of said longitudinal guiding plate opposite saidrotary hook assembly and equipped with a head which is reciprocablebackward and forward in a direction transverse to the guiding plate, soas to clamp an edge of a second article, and in a direction longitudinalto the guiding plate, to form a crumpled position in said edge of saidarticle.
 6. A machine as in claim 2, which comprises a presser footlocated beside a flat surface of said longitudinal guiding plate facingsaid rotary hook assembly and moved in direction transverse to saidguiding plate so as to clamp said articles while the needle is piercingsaid articles, said presser foot having a through-hole, through whichsaid needle passes freely in a direction longitudinal to said guidingplate in synchronism with said movement of said needle.
 7. A machine asin claim 2, which comprises a leather pressing element, situated besidesaid flat side surface of said longitudinal guiding plate opposite saidrotary hook assembly and movable in direction transverse to said guidingplate so as to clamp said articles after each stitch has been performed,while the needle is being extracted and also during a return axialstroke of said needle.
 8. A machine as in claim 2, which comprises a rimpresser positioned over said guiding plate and vertically adjustable foracting on the edges of said articles to be sewn by a shaped headdefining a cavity turned toward said articles.
 9. A machine as in claim8, wherein said shaped head of the rim presser includes two elementsthat act on said articles respectively, and are adjustable independentlyfrom each other for defining mutual positioning of said articles.
 10. Amachine as in claim 2, wherein said arc-like needle and said rotary hookassembly are supported by a head that is inclined so as to determinedifferent working paths for said needle.